Pixel art is the name given to pictures which are drawn pixel-by-pixel. They do not use any line-smoothing techniques and as such, can be reduced to very few colours (typically 16 or fewer). This type of images are common of old console video games (such as the Game Boy) which have very few display pixels and limited colours. Pixel art has increasingly become mainstream and is now being widely used in print media and advertising.
Pixel Art Video Games
Comic Book Pixel Posters